Generally, a compressor used in an air conditioning system of a vehicle inhales a working fluid completely evaporated in an evaporator, converts the working fluid into the state that can be liquefied easily with high pressure and high temperature, and then transfers the working fluid to a condenser.
Such a compressor is classified into a reciprocating type compressor in which a component for compressing a working fluid is substantially reciprocated to compress the working fluid, and a rotary type compressor in which a component for compressing a working fluid is rotated. The reciprocating type compressor includes a crank type compressor that transfers driving force of a drive source using a crank shaft, a swash plate type compressor that transfers driving force using a rotary shaft to which a swash plate is installed, and a wobble plate type compressor using a wobble plate. The rotary type compressor includes a vane rotary type compressor using a rotating rotary shaft and vane, and a scroll type compressor using a rotating scroll and a fixed scroll.
FIGS. 1 and 2 schematically show a general swash plate type compressor, which will be explained with reference to the figures. Front and rear housings 10 and 20 and front and rear cylinder blocks 30 and 30′ define an external appearance and a framework of a swash plate type compressor 1. The front and rear cylinder blocks 30 and 30′ are coupled with each other, and the front and rear housings 10 and 20 are respectively coupled to both sides of the cylinder blocks 30 and 30′.
Discharge chambers 12 and 22 are respectively formed to be concave on surfaces of the front and rear housings 10 and 20, which are in contact with the front and rear cylinder blocks 30 and 30′. The discharge chambers 12 and 22 selectively communicate with a cylinder bores 34, which are provided in the front and rear cylinder blocks 30 and 30′ along an inner peripheral surface of the front and rear housings 10 and 20, by means of valve units 60, which will be described later. A swash plate chamber 31 is formed to be concave on surfaces of the front and rear cylinder blocks 30 and 30′, which are coupled to each other. A rotary shaft 40, which will be described later, is provided to pass through the swash plate chamber 31, and a swash plate 42 coupled to the rotary shaft 40 is positioned in the swash plate chamber 31.
A shaft support hole 32 is provided at the center of the front and rear cylinder blocks 30 and 30′. The shaft support hole 32 is a portion, in which a rotary shaft 40 to be explained later is inserted, and is designed to have an inner diameter such that an outer surface of the rotary shaft 40 is in close contact therewith.
A plurality of the cylinder bores 34 are formed in the front and rear cylinder blocks 30 and 30′. Pistons 50 to be explained later are respectively seated in the cylinder bores 34 and reciprocated to compress a working fluid.
The rotary shaft 40, which is rotated by means of an external drive source, is installed to pass through the shaft support hole 32 and the front housing 10. The swash plate 42 having a substantially disk shape is installed to the rotary shaft 40 slantingly with respect to an extension line of the rotary shaft 40. A cylindrical hub 44 is provided at the center of the swash plate 42, wherein the rotary shaft 40 passes through the hub 44 and is mounted with the swash plate 42. Communication holes 44′ are bored through the hub 44 to communicate with the inside of the rotary shaft 40.
Bearings 45 are coupled to both sides of the hub 44. As shown in FIG. 3, the bearing 45 includes a first race 45a coupled to the swash plate 42, a second race 45b fixed to the front or rear cylinder block 30 or 30′, and a cage 45c coupled between the first and second races 45a and 45b and provided with a plurality of needles B.
A plurality of shoes 46 are installed around a rim of the swash plate 42. The shoes 46 are configured to move along the rim of the swash plate 42.
A flow channel 47 in which a working fluid flows is formed in the rotary shaft 40. The flow channel 47 is formed in the rotary shaft 40 to extend in the lengthwise direction of the rotary shaft 40. The flow channel 47 communicates with the cylinder bores 34 and the communication holes 44′, respectively.
The piston 50 for compressing a working fluid is installed in the cylinder bore 34 to make linear reciprocation therein. The piston 50 is connected to the swash plate 42 with the shoe 46 interposed therebetween, so that the piston 50 linearly reciprocates as the swash plate 42 rotates.
The valve units 60 are respectively installed between the front housing 10 and the front cylinder block 30 and between the rear housing 20 and the rear cylinder block 30′. The valve units 60 selectively communicate the cylinder bore 34 with the discharge chambers 12 and 22 to control discharge of the compressed working fluid.
A muffler 61 is formed in the front and rear cylinder blocks 30 and 30′ to communicate with the discharge chambers 12 and 22. The muffler 61 serves to reduce pulsation and noise of a working fluid.
However, the aforementioned conventional compressor has the following problems.
Since the communication holes 44′ are formed through the hub 44 of the swash plate 42, there needs a separate process for forming the communication holes 44′ when the swash plate 42 is manufactured. Thus, there is a problem in that the swash plate 42 causes the man-hour needed for the works and the manufacturing time to increase.